intro to med Flashcards
what is a drug
pharmacologically active ingredients
API active pharmaceutical ingredient
what is a medicine
means of administrating a drug in a safe and efficient manner - contains drug and excipients
what is an excipients
inactive substance used as a carrier for the active ingredients of a medication
name the routes of administration
oral,
rectal,
topical,
parenteral,
pulmonary routes,
nasal,
ocular (eyes),
otic (ears)
problems associated with different administration
GI -pH,gastric emptying,enzymes,bile
respiratory tract - mucociliary
rectal- poor retention of small dosage, small SA compare to GI tract.
A good medicine has (4 things)
dose uniformity - accurate dose
patient acceptability - pleasant to use
stability long shelf life
directions of use
name the 3 types of powder
effervescent powders - contain acid and carbonate
dusting powders - talc
powders for syrup - for kids and when formulation are unstable as a solution or a suspension.
what is granulation
approach to prevent segregation by forming granules which contain correct ratio of ingredients.
ADV of powders
-faster dissolution rate
-more stable than liquid
- convenient for high dose drugs
versatile dosage form - can be customised.
DISADVANTAGES of powders
- not suitable for drugs which are inactivated in the stomach
- stability challanges - Difficult to protect hygroscopic and deliquescent substances
- less convenient - carry and prepare
what is a tablet
formed by compression of powder or graules.
ADVANTAGES of tablets
- accurate dosing
-long shelf life
-controlled release options.
-taste masking
DISADVANTAGE of tablets
- difficulty swallowing
-delayed onset - may take longer to absorb compared to liquids and powders.
-inactivation in stomach acid.
how does a tablet press work
- A die is filled with powder/granules
- mechanical force is applied between upper and lower punches
- Tablet is ejected.
what is dissolution and why is it important
e process by which a substance (often a solid) dissolves in a solvent to form a solution.
sold substance need to be dissolved in order to be absorbed into the GI
what is the dissolution rate
rate at which drug particles become individually dispersed within a solvent
noyes -whitney equation -
4 things
-SA
- solubility in the diffusion layer
-concentration of the drug
-thickness of the diffusion layer
tablet excipients
filler/diluent - bulking agent - lactose
disintegrant - enables the breakdown by rupturing the tablet. -starch
absorption enhancers - modulates -permeability of a membrane - surafcants
Binder - mechanical strength - cellulose
dissolution enhancer- increases solubility - magnesium oxide
glidant- improves flowability of the powder - magnesium stearate
lubricant -ensures ejection from the die - magnesium stearate or stearic acid.
what are 4 drug release
- immediate release - rapid
-extended/prolonged release - releases slowly and constant rate
-pulsatile release - 2 or more pulses
-delayed release - delayed after some time from administration (enteric coat)
what is the enteric coating and when are they used(3) ?
pH sensitive polymers that are insoluble in acid but dissolve in natural or slightly alkaline conditions of the gut.
-drug is inactivated or destroyed by acid in stomach
-drug is irritating to the gastric mucosa
-when bypass from stomach enhances absorption.
what is a capsule
edible packages filled with medicine to produce a unit dose
what is a solution
mixture of 2 or more components that form a single phase that is homogeneous down to the molecular level.
excipients
flavouring agent - palatable
colouring agent - make it attractive
antioxidants - stability
pH adjusters - so site of administration isnt irritated
viscosity enhancer - easy to handle
preservatives - to preserve multidose preparations.
solubility enhancer - maintains solubility of the drug
what is a suspension
solid within a liquid vehicle. does not dissolve
excipients of suspensions
preservatives - prevent microbial contamination
buffers - maintain pH - suppress solubility
chemical stabilisers -
suspending agents - increase the density of the suspensions or may reduce sedimentation rate
flocculation modifiers - adjust the extent to which floccules form
what are the biopharmaceutical considerations ?
- in suspensions and solutions disintegration rate is surpassed.
bioavaliability - aqueous solutions, aqueous suspensions and then solid dosage.
What is an emulsion
dispersions of 2 or more immiscible liquids.
example diazepam
how many phases are there in emulsion and what are they
2 phases - water and oil
(o/w) (w/o)
continuous (external) and disperse phases (internal)
adv of oil in water phase o/w
mask unpleasant scent and suppress taste
o/w are less greasy so are more accepted by patients in topical drugs.
challenges with emulsion stability
- separation into its constituent phases - cracking
what effects the stability
choice of oil,
emulsifier,
temperature
droplet size.
what excipients are commonly used to improve stability
emulsifiers- surfactants proteins e.g. gelatine
polysaccharides e.g. cellulose
talc or Mg(OH)2.
what is it called when a gent has a hydrophobic and hydrophilic part
amphiphiles
what is an ointment
semi-solid fatty preparations
what are ointments made of
and how does the hydration effect the drug delivery ?
-soft, hard and liquid paraffin.
prevents trans epidermal water loss, hydrating skin.
hydration of the outermost layer increases flux of drug delivered.
can be used to provide prolonged drug delivery
what is the chemical stability of o/w emulsion
chemical degradation
high SA.
microscopic oil globules present huge area for light and O2 catalysed reaction.
how is this counteracted ?
add oil soluble antioxidant
vitamin E, BHA,BHT
microbiological - stability
what is added ?
o/w microbes go well in water phase
use oil phased as food
this destabilises the emulsion
preservatives added
why should we be careful with the choice of preservatives ?
it should not partition into oil phase
becomes ineffective
should not interact with the emulsifier
destabilise the emulsion
